Turning 18 as a US citizen in the UK: when your own filing starts

When does a US citizen's own filing duty begin

It begins in the first year the citizen's own income passes the threshold that applies to them, at any age. Publication 501 (opens the official IRS page in a new tab) sets no minimum age, and age only enters the test at 65. A child with enough income files a return like anyone else, and money a child earns is the child's income, not the parent's.

Living in Britain does not move the start date, because US citizens and resident aliens abroad (opens the official IRS page in a new tab) follow the same filing rules as people in the United States. What differs for a young person is the threshold. Someone who can be claimed as a dependant is tested under a separate table in Publication 501 on unearned income, earned income and gross income, and a return is required if any one is passed. A teenager with savings most often crosses the unearned income line.

Two other triggers matter. Self-employed earnings, such as tutoring or selling online, require a return at a far lower level. And once nobody can claim you, the single filer threshold applies, which broadly follows the standard deduction of $15,750 for tax year 2025. PAYE wages count in full, because the test uses gross income, as our post on filing on a low income explains.

What changes on turning 18 as a US citizen abroad

Responsibility changes at once, and the tax rules change less than most families expect. From 18 the obligations are plainly the young adult's to meet, with no parent signing for them. A parent may still be able to claim them as a dependant, though, and the special tax on a child's investment income can still apply.

The dependant point turns on the qualifying child tests in Publication 501. The age test is met by someone under 19 at the end of the year, or a full-time student under 24, and support and residence tests apply as well. While they are met, the dependant table still sets the young adult's threshold. Our post on American students at UK universities covers the student years.

The tax on a child's unearned income, worked out on Form 8615 and often called the kiddie tax, also outlasts the birthday. The IRS instructions apply it to a child under 18 at the end of the year, and also to an 18-year-old or a full-time student aged 19 to 23 whose earned income was not more than half of their own support, where unearned income passes an annual limit. A self-supporting apprentice usually falls outside it; a student on family money may not.

• Signing: the young adult signs their own Form 1040 and FBAR
• Filing threshold: still the dependant table while a parent can claim them
• Kiddie tax: possible at 18, and for full-time students up to 23
• A parent's election to report a child's interest and dividends: under 19 only, or under 24 for a student

Should your parents have filed for you before 18

Only for the years in which something was actually due. Publication 501 says that where a child must file but cannot, because of age or for another reason, a parent, guardian or other legally responsible person files the return for them. FinCEN says the same of the FBAR. In a year when nothing was due, nobody was in default.

The return and the report were still the child's own; a parent signs the child's name, then their own as parent for minor child. For the FBAR, FinCEN's guidance (opens the official FinCEN page in a new tab) says a child is generally responsible for their own report, and where the child cannot file, a parent or guardian files and signs it electronically as Parent/Guardian filing for child. The threshold is tested on the child's accounts alone, $10,000 in aggregate at any time in the calendar year, and the parent's own accounts play no part in it.

Publication 501 adds that if a child does not pay the tax due on their earnings, the parent is liable for it. A parent's own FBAR for a child's account they controlled is covered in our posts on Child Trust Funds and Premium Bonds and Junior ISAs.

Which childhood years actually need fixing

Often none. Each year from birth is tested on its own: did the child's income require a return under that year's thresholds, and did the highest balances of the child's foreign accounts together pass the FBAR threshold. A year that meets neither test has nothing to put right.

The work is a schedule, one calendar year at a time. List every UK account in the young person's name, from Junior ISAs and Child Trust Funds to Premium Bonds, with its highest balance, and beside it the year's interest, dividends, fund distributions, wages and self-employed earnings. Each year is tested against its own thresholds. Every year then falls into one of the rows below. The sorting is ours, not the IRS's.

Where a year did need a return, our post on owing nothing applies: the assessment period starts only when a return is filed, and a nil bill does not close the year.

• No return due and no FBAR due: nothing to file; keep the schedule as evidence
• FBAR due but no return due: file the late FBAR through FinCEN with a reason for the delay
• Return due because of investment income or self-employed earnings: a late return, usually inside a catch-up procedure
• Return and FBAR both due: deal with the years together so returns and reports agree
• Failure was knowing rather than a mistake: take advice before filing anything

Do you need Streamlined or just this year's return

If no return was ever due, you do not need Streamlined for returns: you begin filing in the first year your income requires it. Late FBARs alone usually go to FinCEN with an explanation. Streamlined becomes the question when returns were due and missed, and the failure was not wilful.

The Streamlined Foreign Offshore Procedures (opens the official IRS page in a new tab) ask for three years of returns and six years of FBARs, counted back from the most recent years whose due dates have passed. For someone who has just turned 18, that window may be largely or wholly childhood years. The IRS page sets no separate rule for years spent as a minor. The taxpayer signs Form 14653 certifying non-wilful conduct, which the IRS describes as negligence, inadvertence, mistake or a good faith misunderstanding of the law, and in our view the narrative should say who managed the accounts then. Our post on which years Streamlined covers shows how the window is set.

The route still matters. The Foreign route carries no penalty beyond tax and interest for those who qualify, and someone raised in Britain usually meets its test of 330 full days outside the United States in one of the years. The Domestic route (opens the official IRS page in a new tab) charges a 5% miscellaneous offshore penalty. Both require non-wilful conduct certified in writing, and neither is available once the IRS has opened an examination. Streamlined can realistically be used once, so a young adult with only late FBARs may not need it at all. Our IRS streamlined filing service starts by sorting the years.

How might this look for an apprentice in Glasgow

Take a dual national born in March 2008 to an American father and a Scottish mother, who turns 18 in March 2026 and starts an engineering apprenticeship. She has a current account, a savings account and a Junior ISA that her Child Trust Fund was transferred into. Nothing has ever been filed in her name.

Her schedule settles most of it. Her Saturday job wages were well below the dependant earned income test, and the ISA's distributions stayed under the unearned income line, so no return was ever due. In two recent years, though, her three accounts together passed the FBAR threshold, so reports were due in her name, signed by her father.

She therefore needs no Streamlined submission for returns. The two reports are filed late on FinCEN Form 114 with a short reason, as our post on late FBARs describes, and her father checks his own. For 2026, whether she files turns on whether her father can still claim her and on her apprentice wage against the right table. Our post on ISAs on the FBAR and Form 8938 covers the fund question she should raise next.

Change one fact. Had she tutored for pay at 16 on her own account, a return could have been due at a far lower level of earnings, with the UK totalisation agreement (opens the official SSA page in a new tab) to consider, and Streamlined would come into view.

What should a new adult set up from now on

Three things: a Social Security number if you have none, a yearly account schedule, and a calendar. No return can be filed without the number, and an adult applying for a first one from the UK attends an in-person interview, as our post on getting a Social Security number from the UK explains.

The calendar is short. A calendar-year return is due on 15 April, and a filer living abroad has an automatic extension (opens the official IRS page in a new tab) to 15 June, though interest runs from the original date. The FBAR is due 15 April, extended automatically to 15 October and is filed with FinCEN, never with the return. Our individual tax returns and foreign income and FBAR reporting services cover both, and the Form 1040 page describes the return.

For anyone thinking of renouncing, the Instructions for Form 8854 (opens the official IRS page in a new tab) excuse certain dual citizens from birth, and people who expatriate before age 18 and a half with no more than ten years of US residence, from the net worth and tax liability tests. Neither removes the five-year compliance certification. Our post on covered expatriate tests has the detail, and our guide for people behind on US taxes in the UK shows the full sequence.

• Confirm citizenship, then find or apply for a Social Security number
• Build the account schedule back to birth, one calendar year at a time
• Mark each year: nothing due, FBAR only, return due, or both
• Before any renunciation, make sure five years can be certified